1. Technical Field
The present invention relates to an ultrasonic device, an ultrasonic module, an electronic apparatus, and an ultrasonic measurement apparatus.
2. Related Art
In the past, there has been known an ultrasonic device provided with an element substrate having ultrasonic vibrators each vibrating in accordance with a signal input to output an ultrasonic wave, and first terminal parts respectively connected to the ultrasonic vibrators, and a wiring board having second terminal parts electrically connected to respective terminals of the element substrate (see, e.g., JP-A-2014-209728 (Document 1)).
In the ultrasonic device described in Document 1, the element substrate having opening parts is provided with a support film for covering the opening parts, and ultrasonic transducers each having a lower-part electrode, a piezoelectric film, and an upper-part electrode stacked on one another are disposed on the support film. Further, on the surface of the opening parts of the element substrate, there is disposed a back plate (a reinforcing plate) for suppressing a back wave. In such an ultrasonic device, reduction in thickness and miniaturization can be realized compared to the ultrasonic device using a bulk-type piezoelectric body.
Incidentally, in the case of inspecting, for example, a part in a living body using an ultrasonic device, a liquid such as a gel is applied to the ultrasonic emission side of the ultrasonic device so that air does not intervene between the ultrasonic device and the living body. However, if the ultrasonic transducers and electrodes are disposed on the element side surfaces of the element substrate as in Document 1 described above, a liquid such as a water droplet adheres to become a cause of a false operation or a failure. Although it is also possible to adopt a configuration of providing a protective film for achieving a waterproof property, if such a protective film is disposed on the emission side of the ultrasonic wave, the ultrasonic wave is reflected by the protective film due to the difference in ultrasonic impedance, and an accurate inspection using the ultrasonic wave cannot be performed.
Further, in such a configuration as described in Document 1, it is possible to adopt a configuration of outputting the ultrasonic wave from the surface on the opening part side of the element substrate. In such a configuration, it is possible to sufficiently ensure the waterproof property with respect to the electrode lines connected to the piezoelectric elements (the lower-part electrodes, the piezoelectric films, and the upper-part electrodes) and the electrodes.
In contrast, in the ultrasonic transducers each shaped like a thin film, since the thin element substrate is used, there is a necessity of bonding a reinforcing plate (a sealing plate) to thereby reinforce the element substrate. Here, since it is not possible to adopt a configuration of disposing the reinforcing plate on a transmission/reception surface for the ultrasonic wave out of the element substrate (the reinforcing plate becomes an obstacle to the ultrasonic transmission/reception), it results that the reinforcing plate is disposed on the rear surface side of the element substrate. However, as described above, in the configuration in which the piezoelectric elements and the electrode lines are disposed on the rear surface side of the element substrate, it results that the terminal parts for achieving the connection to the wiring board are also disposed on the rear surface side. FIG. 7 shows an example of a configuration of a related-art ultrasonic device. As shown in FIG. 7, in such a configuration described above, it results that flexible printed circuits (FPC) 71 are connected to the terminal parts (electrode pads 414P) of the element substrate 41, and the FPC 71 are drawn through the opening 73 provided to the reinforcing plate (the sealing plate 72) and are connected to wiring terminal parts provided to the wiring board. In this case, there is a possibility that the element substrate 41 is lifted or tilted due to the reactive force of the FPC 71, and the control of the ultrasonic transmission/reception direction becomes difficult. Further, there is also a possibility that the FPC is broken at a corner part of the opening 73 of the reinforcing plate 72, and the wiring reliability is degraded.